Dual salt moisture indicating composition



March 10, 1970 w. o KRAusE l 3399316 I v DUAL SALT HOISTUBE IHDIC'I'IHGCOMPOSITIN Filed Aug. 19. 1968 3 Shets-Shqet 1 F/i/P Wm f7.

62 M175? a leaf/5f Semmesadsemmes March 10,1970

Filed Aug. 19, 1968 w. o. KRAusE 3,499,316

DUAL SALT MOISTURE INDICATING COMPOSITION v l 5 Sheets-Shawl;- 2

' March 1o, 1970 w. o. KRAUSE 3,499,316

DUAL SALT MOISTURE INDICATING COMPOSITION Filed Aug. 19, 1968 3Sheets-Sheet 3 mmesandmmes rmi/v5 3,499,316 DUAL SALT MOISTUREINDICATING COMPOSITION Walter O. Krause, Chesapeake, Va., assignor toVirginia Chemicals, Inc., West Norfolk, Va., a corporation of VirginiaFiled Aug. 19, 1968, Ser. No. 753,655 Int. Cl. Gln 33/00; Clg 51 /08U.S. Cl. 73--61.1 5 Claims ABSTRACT OF THE DISCLOSUREMoisture-indicating materials of the type used in refrigerant systems todetect moisture content which may have a deleterious effect upon theSystem capabilities, particularly, a dual bromide salt moistureindicator composition which undergoes a reversible color change aswetted, indicating the degree of moisture within the refrigerant system.

BACKGROUND OF THE INVENTION Field of the invention In refrigerantsystems and related liquid systems, a great deal of recent attention hasbeen given to the detection of water or moisture content which has adeleterious effect upon system capabilities. Cobaltous bromide has beenemployed as an impregnant for glass fiber or paper. Cobaltous bromideitself undergoes a dominant color change from green to pink, as itbecomes saturated with water. However, the color change of cobaltousbromide is fairly nite with respect to the percentage of water detected,that is the cobaltous Ibromide rapidly completes its color change withina narrow percentage range of moisture. Accordingly, attention has beengiven to developing related compositions which would have variant colorindicating characteristics as system needs dictate.

Description of the prior art Cobaltous bromide moisture indicators maybe positioned in a moisture indicator housing, of the type illustratedand claimed in Patent 3,085,424 and assigned to assignee herein. Theliquid phase indicator may be of a cobaltous bromide type applied to amat of inert bers, as disclosed in Patent No. 2,836,974 or, as appliedto a cellulosic paper, as set forth in Patent 2,761,312. In both casesthe color indicators were used in refrigerant systems having arefrigerant liquid of low water solubility.

A principal piror art teaching of the employment of salts such asmagnesium chloride, calcium chloride and aluminum chloride together withcobalt chloride is set forth in Applied Biology (M. E. Solomon): The Useof Cobalt Salts As Indicators of Humidity and Moisture, pages 75-85.

SUMMARY OF THE INVENTION According to the present invention the colorindicating characteristics of the cobalt salt are considerably varied byemploying dual salts such as the following:

(1) Cobaltous acetate with another acetate salt;

(2) Cobaltous bromide with bromides of barium or magnesium; and

(3) Dual bromide salt combinations, such as cobaltous bromide and abromide salt of zinc cadmium or mercury.

The color change results thus achieved, are illustrated in FIGS. 1, 2,3, 4, 5, and 6.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a graph depictingapproximate color changes by hue of the dual acetate salts: cobaltousacetate and 3,499,316 Patented Mar. 10, 1970 fw t acetate Zinc, cadmiumand mercury, as affected by water content;

FIG. 2 is a corresponding graph of the dual bromide salts: cobaltousbromide and bromide of zinc, cadmium and mercury;

FIG. 3 is a like graph of the dual bromide salts: cobaltous bromide andbromide of barium, magnesium and cadmium;

FIG. 4 is a graph depicting approximate color change by hue with theincreasing of the ratio of cadmium bromide to cobalt bromide;

FIG. 5 is a graph depicting approximate color change by hue with theincreasing of the salt concentration;

FIG. 6 is a graph depicting approximate color changes of the cobaltousbromide-cadmium bromide indicator in operating refrigeration units.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Free and dissolved Water inrefrigeration systems has always been a major problem. The presence ofmoisture in these systems can lead to some undesirable effects such as:

(l) Chemical reaction with oil or refrigerant to form acidic materials,tars and varnishes.

(2) Clogging of metering devices due to freeze up.

(3) Lowering of the dielectric of motor insulation in hermetic andsemihermetic motors resulting in motor failure.

(4) Enhanced probability for copper plating.

As a result, manufacturers of refrigeration equipment as well as theinstalling contractor and service engineer carry out expensive and/ortime consuming procedures to obtain the degree of internal dryness whichleads to reliable and prolonged system operation. These proceduresgenerally consist of high vacuum techniques combined with elevatedtemperatures. However, even when these techniques are followed, theconcentration of moisture in the system cannot be specificallydetermined unless expensive and time consuming analytical techniques areused. Some manufacturers carry out these procedures on a small segmentof their daily production to assure themselves that their manufacturingprocedures are conforming to expectations. Further, dehydratorscontaining desiccating materials are installed for further protection.

Since analysis of each assembly is economically unfeasible to themanufacture and impossible for eld assembled equipment, moistureindicators have been used. These indicators reversibly change color withchanges in relative saturation of water dissolved in a particularrefrigerant.

The working portion of these indicators generally consist of a cobaltsalt, preferable cobalt bromide, deposited on paper or some othermaterial such as polyester or fiberglass.

The relative concentration of the cobalt salt to the cellulose or paperbase material is held so that a significant change in color is obtainedwhen the relative saturation of water in refrigerant reaches 4 to 5% ofcomplete saturation. Generally no further color change occurs after therelative saturation reaches about 17%. The color obtained below 5%relative saturation is considered the dry color while that obtainedabove 17% is considered the wet color. It is postulated that thecellulose-cobalt bromide forms a complex salt with differentcharacteristics than the cobalt salt alone.

When no complex is formed such as a polyester cobalt bromide colorchanges occur at a lower relative saturation of water in refrigerants.This change occurs at about 1.2 to 2.4% relative saturation with the wetcolor occurring above 2.4% and the dry color below 1.2% relativesaturation. The degree of sensitivity to low dissolved moisture levelsis desirable in many cases. This is especially true when properdehydration of equipment has been carried out. These systems, then, havean extremely low concentration of moisture in the circulatingrefrigerant when iirst placed into operation. Later, through normal orbut generally adverse operating conditions deterioration of the organicconstituents such as oil or motor insulation Water is formed and theconcentration of dissolved water rises. If deterioration should continueequipment failure will result. Accordingly, a monitoring system such asa moisture indicator changing color at low moisture levels is vital.Should color change occur proper procedure can be taken to correct theadverse conditions.

Under a given set of operating conditions, system sensitivity tochemical or thermal deterioration varies with selection of componentsmaking up the motor compressor. Some components are more sensitive thanothers to the environment and depending upon their chemical naturecontribute more or less water to the system during deterioration. Theamount of material used also bears on the quantity of water contributedto the system.

Considering moisture increase in a system as an indication of chemicaldeterioration, a moisture indicator changing from a dry to a wet colorwould signal that this deterioration is occurring. With systems ofvarying sensitivities and ability to create water, moisture indicatorsshould be designed for specic refrigeration systems. Rather,standardized moisture indicators are applied to any and all systems. Bychanging the ratio of cobaltous bromide to the paper base the standardindicators can be made to show color shifts between narrow limits.

Indicators can be prepared that will show color changes at high moisturelevels or at low moisture levels. This can be done by the addition ofwater soluble salts of metals in Groups II-A and lI-B in the PeriodicTable to cobaltous controlled very speciiically with regard to normalconcentrations of the salts as well as the ratio of concentration of onesalt to another.

After drying the treated paper, the paper `can be cut to variousgeometric configurations to be mounted in a hermetic device having asight glass and proper fittings for installation in refrigerationsystems. The color change of the indicator with changing concentrationsof dissolved water in the refrigerant can be observed through the sightglass.

Examples of some of the various types of moisture indicator combinationsare shown in the graphs FIGS. 1-6. For simplicity purposes the colorchanges are shown as change by hue rather than specific colors since thedry color is not always at the same hue. For example, the dry color fora cobaltous bromide based indicator has a Color Harmony Value of 15 icwhile an indicator prepared with cobalt chloride mercuric chloride has aColor Harmony Value of 12'1/2 gc in its dry state.

The base line of the graphs is considered as the color of the indicatorin its dry state. This color is generally a blue color. The graph showsthe indicator going through its intermediate stages of lavendar, lilac,etc. The termination point of each graph line is that point at which adefinite pink or wet color is reached. This is generally equivalent to aColor Harmony Value of ll ca.

The addition of salts to Group lI-B to sensitize these elements appearsto eliminate the dry anhydrous color so that one continuously approachesthe intermediate colors with increasing amounts (based on the ratio ofthe two salts) of the II-B salts. In this way the number of hues theindicator must go through to reach the pink or wet color, is constantlyreduced.

The effect of the addition of the dual salts on the color changecharacteristics of Whatman No. l filter paper are set forth in Tablesl-4 below:

TABLE 1.-EFFECT OF THE ADDITION OF VARIOUS SALTS ON THE COLOR CHANGECHARACTERISTICS OF WHATMAN NO. 1 FILTER PAPER TREATED WITH CoBrz ColorHarmony Value Percent H2O N o salt in H-l51 Added 211Br2 CdBrg HgBrgMgBrs CaBrg BaBm LigBr C0(NO;)2

0 151e 13% ge 13% ie 13% ie 16 la 171a 16 la 16 la 13 lc 1 151e 13% go13% ic 13% ie 161s. 17 la 16 la 1619. 131e 2 151e 13 ge 13% ic 13% io 16la 17 la 16 la 16 la 13 ia 3.. 15 ic 12% ee 12% ge 12% ge 16 la 17 la 16la 16 la 13 ic 3.2 15 ic 12% ec 12% ec 12% ee 1613. 17 la 161:1. 16 la13 ic 3.50 15 ic 12% ec 12% ee 12% se 16 la 17 la 161a 1610. 13ie 3.75.15 ic 12 ce 11 ec 11 eo 16 ia 17 ia 16 ia 16 ia 13 ic 4.00. 15 gc 12 ec11 ee 11 ec 16 ia 17 ia 16 ia 16 ia 13 ic 4.50 15 ge 11 ca 10 ec 10 ec16 ga 17 ga 16 ga 16 ga 13 ie 5.00. 15 ge 11 ca 10 ec 10 ec 16 ga 17 ga16 ga 16 ga 131e 6.00 14 ec 7 ca 7 ca 16 ga 17 ga 16 ga 16 ga 13 go7.00. 7 ca 7 17 ec 17 ga 16 ec 16 eo 12 ec 8.00 16 ce 16 ga 14 ee 14 ee10 ca 9.00- 14 ee 17 ea 13% ca 13 ea 10,00 13 ca 17 ca 12% ca 12 ca11.00 12 ea 17 ea 12 ea 12 ca 12.00.- 12 ca 14 ca 12 ca 12 ca 13.00. 12ca 12% ca 12 ca l2 ca 14.00 12 ca 12 ea 12 ca l2 ca bromide.Furthermore, other cobaltous salts such as the nitrate, acetate andsulfate with cobalt chloride and bromide have a color change shiftingeffect. Addition of Group II-B salts to the cobaltous bromide orchloride sensitizes the moisture indicator-that isco1or shifts from dry"to wet occur at a lower water concentration level. On the other hand,salts of Group II-A have the opposite effect.

By varying the ratio of one salt to another and/or by varying the ratioof salt mixture to the paper base one can obtain moisture indicators,with color shifts in any desired range depending upon the requirementsof the refrigeration system to which it is applied.

The moisture indicators are prepared by immersing unsized paper, such asWhatman No. 1 laboratory grade filter paper in the solution of thesalts. The solutions are TABLE 2.-EFFECT OF THE ADDITION OF VARIOUSSALTS ON THE COLOR CHANGE CHARACTERISTICS OF WHAT- MAN NO. 1 FILTERPAPER WITH C0(AC)2 Percent Color Harmony Value H2O in H-151 Co(Ac)2Zn(Ac)2 Cd(Ac)2 Hg(Ac)2 Co(NO5)z 0 12 ie 11 gc 12 gc 11 gc 11 ic 12 ic1l gc 12 gc 11 gc 11 ic 12 ga 10 ec 12 ge 11 gc 101e 12 ga 10 ee 1l ge11 ec 10 ie 12 ga 10 ec 11 gc 11 ec 10 gc 1l gc 10 ec 11 gc 11 ee 10 gc11 gc 10 ec 11 ec 11 ee 10 gc 10 ec 11 ee 10 ee 10 gc 10 ee 11 ce 10 ee10 gc 10 ec 11 ec 10 ee 9 gc 10 cb 10 cb 10 ec 9 gc 10 cb 10 cb 9 ca 9ea 8.00 11 ca 10 cb 10 cb 9 ca 9 ea TABLE 3.-EFFECT OF INCREASING THERATIO OF CADMIUM BROMIDE TO COBALT BROMIDE ON THE COLOR CHANGECHARACTERISTICS OF TREATED WHATMAN NO. 1 FILTER PAPER Color HarmonyValue Molar Ratio of CoBr2 to CdBrg CoBrz=l H2O in ISI-151, Percent byWt 3/ 1 1% 2 3 4 5 13% ic 13% gc 13% gc 13% ic 13 ic 13 ga 13% ie 13% gc13% gc 13 ic 13 1c 13 ga 13% ge 14 14 ec 12% ec 12 c3. 12% ga ec 12 ec12% ca 12 ca 12% ea 7 cb 7 Cb 12% ca 7 eb 7 cb cb 7 cb 7 cb 7 cb 7 cb 7cb 7 cb 7 cb 7 cb 7 cb 7 cb 7 cb 7 eb 7 cb 7 cb 12% ec 12 ca 12 ca TABLE4.-EFFECT OF INCREASING THE SALT CONCEN- TRATION IN THE COLORCHARACTERISTICS OF WHAT- NO. 1 FILTER PAPER TREATED WITH C0Br2 AND ColorHarmony Value Amount Salt in 100 cc. H2O, g.

Percent H2O 5.00 g. CoBr2 10.00 g. CoBrg 20.00 g. CoBr2 in H-ll 7.85 g.CdBrz 15.70 g. CdBr2 31.40 g. CdBr2 o 13%1@ 1410 15 ne 20 13% ic 141e 15ne prlsmg: 13% gc 13 ic 15 nc ec 13 ic 15 ne 12% ca 13 ic 15 nc 12% ca13 ic 15 nc 10 cb 12% gc 15 nc 7 cb 12% gc 15 nc 30 7 cb 11 gc 12% ic-7cb 11ec 12%ie 6.00 7 ob 9 gc 12 gc prlsmg:

TABLE 5.-COLOR CALIBRATION OF DUAL SYSTEM PAPER BASE MOISTURE INDICATORSTREATED WITH COBrz AND CdBrz CoBr2=0.023M/LITER=1 35 11-12 prlsmgr 0.750.825 1.00 H2O, 0.1, CdBre CdBr2 CdBrz p.p.m. T., F. percent 14 gc 13%gc 13% gc 2 6 S8 2. 1 14 gc 13% gc 13% gc 2 5 84 2. 3 14 gc 13 c 13 gc 29 84 2. 6 12% ec 12% ec 12% ec 3 6 83 3. 4 13 ec 11 ec 11 ec 6 1 76 7. 112 ca 11 ec 11 ec 11 5 78 12. 5

risin R-22 p g 13% ic 13% ec 13% ic 9. 7 74 0. 80 13% gc 13% gc 13% gc10. 5 74 0.85 13% gc 13% gc 12% gc 19. 0 74 1. 54 13% ec 12% ec 12% ec21. 4 74 1. 73 13% ec 12% ec 12% ec 22.0 74 1.79 13% ec 12% ec 12% ec30. 0 74 2. 46 12% ec 12 ec 12 ec 43. 3 74 3. 52 50 12% ec 12 ec 12 ee48. 0 74 3. 90 11 ca 57. 0 4. 62

C B M 2,460,065 o 12-0.01961 -l 2,526,938 0.75 OdBr: 1.00 CdBrz 1.25CdBrz H2O, p.p.m. c/c.. 55 2,761,312 134513 134514 13 gc 5. s 0.473,173,880 13% ic 13% gc 13 gc 7. 0, 7. 0; 7. 1 0. 57; 0. 57; 0.57 13% gc13%10 13 gc 8. 7; .9; 10. 3 0. 0; .72 13 gc 12% gc 12 ec 5; 117. 56 1.35; 1. 42; 1. 47

8. 13 ca 12% ea 12 ea 20. 2; 19. 6; 1. 64; 1. 59; 1. 57

19. 3 12% e3 12 ec 111e 34. e; 335. 4i 2. s; 2. 9; 3. 9 60 5. 12% ec 12ec 11 ca 61. 0, 558. 3; 5. 0; 4. 7; 4.7

8. 3 12 ca 11 ca 10 ca 64; 64; 64 5. 2; 5. 2; 5. 2

Color calibration of a dual salt system involving cobaltous bromide andcadmium bromide is set forth in Table 4 and color change points of this`dual salt indicator are set forth in Table 5.

Manifestly, the concentration of the dual salts may be varied, as setforth in Tables 4 and 5 and otherwise, without departing from the spiritand scope of invention.

What is claimed is:

1. A dual salt moisture indicating composition com- (A) a basecellulosic paper impregnated with;

(B) cobaltous bromide; and

(C) a bromide salt from the group consisting of zinc,

cadmium, and mercury.

2. A dual salt moisture indicating composition com- (A) a basecellulosic paper impregnated with cobaltous bromide and zinc bromide. 3.A dual salt moisture indicating composition com- (A) a base cellulosicpaper impregnated with; (B) cobaltous bromide; and (C) cadmium bromide.

4. A dual salt moisture indicating composition as in claim 3, whereinsaid cadmium bromide is in the proportion of 1/2 to 2 times the amountof cobaltous bromide.

5. A dual salt moisture indicating composition com- (A) a basecellulosic paper impregnated with;

(B) cobaltous bromide; and (C) mercury bromide.

References Cited UNITED STATES PATENTS LOUIS R. PRINCE, Primary ExaminerJOSEPH W. ROSKOS, Assistant Examiner U.S. Cl. X.R.

